The invention concerns a printable image support material for thermal image transfer onto flat porous surfaces, especially an ink-jet printable thermal transfer paper.
There are various methods to transfer individual, personal images or designs onto textiles. These designs are printed on release paper or transfer paper using various printing methods such as the thermal dye diffusion transfer process (D2T2), the ink-jet printing method or the toner procedure (electrophotography) and then transferred by heat or pressure to the textile material while the paper backing is removed.
One of these procedures is described in DE 26 53 654 A1, which discloses the creation of long-life, xerographically produced images on cloth. A silicon-coated sheet with a coating layer on top is produced on which the image will be created xerographically. A disadvantage of the transfer paper with silicon coating is that the silicon residue remains on the fibres of the textile backing during the release process after the image is transferred.
U.S. Pat. No. 5,501,902 teaches a printable paper is presented which contains a first polymer layer and an ink-jet printable second layer with film-forming binder, a fine-grained thermoplastic polymer and ink viscosity modifying agent. The images transferred to the textile surface with the help of this transfer paper under the influence of heat and pressure exhibit a high color density while the polymer layer laminate transferred with the images adheres very well to the textile surface. A disadvantage of the transfer paper is that the viscosity-modifying agent usually used is a hydrophilic agent such as polyethylene glycol or polyvinyl alcohol. This agent has a positive effect on the binding ability, however it has a negative effect on the wash fastness due to its water solubility.
DE 299 02 145 U describes a transfer paper which comprises a color receiving layer containing a finely particulate organic pigment and silica. Silica has a favorable effect on the color density. However, silica can only be added in a limited amount. At an amount of more than 15 wt. % transfer problems exist. The organic pigment melts at high temperature and forms a film. But the film is weakened if a large amount of silica is included in the film. The image transfer with such films is difficult.
In addition the ink-jet papers mentioned above are hot peel products. However, if the size of a printed image increases, it becomes difficult to keep the entire image before peeling the support off the textile. The textile may become yellowish as a result of long time heating at high temperature. Furthermore, the image transfer is not complete and the image quality is adversely affected.
It is therefore an object of the present invention to provide an improved image transfer material which does not show the above-mentioned disadvantages. In particular, the improved image transfer material shall allow the image on the textile material to be separated without heating, e.g. at room temperature, and shall satisfy the requirement of providing high ink absorption, that after having been transferred to a textile material still presents excellent optical qualities, in particular high color density, and which, on a textile material, shows high fastness to washing.
These objects are achieved by a printable image transfer material which comprises a support, an intermediate release layer containing a thermoplastic polymer with a surface tension of about 15 to 30 dyn/cm, and an image receiving layer.
The aforementioned objects are also achieved with a printable image transfer material comprising a support, a first layer overlaying the front side of the support material, said first layer containing a thermoplastic polymer with a surface tension of about 15 to 30 dyn/cm, a second layer overlaying the first layer, said second layer containing a polymer having a melt index of between 2 and 10 (ASTM D 1238), and an image receiving layer overlaying the second layer, said receiving layer containing a water dispersible binder, a finely particulate organic pigment, and silica.